New to this, so Hello and apologies if this is in the wrong forum/format - Ive browsed about before posting and it looks right. Anyway...

I'm planning on flying UK to Canada later in the year.

Edinburgh (EDI) -> Seattle (SEA) (via Amsterdam, NWA/KLM)
Seattle -> Kelowna (YLW) (Alaska Airlines)

Only flown long distance once before and went direct and budget (Globespan).


Ive three main areas of questions:
1. In Seattle, do I need to go through customs? Is it straightforward getting my luggage from NWA and checking in for AlaskaAirlines? Got 4 hours between the flights. What if my flight is late arriving in Seattle, will insurance cover me for another flight to Canada?

2. Is there any benefit to booking with a travel agent? Seems to be cheaper if I book EDI - SEA with opodo and SEA - YLW direct with airline.

3. Can someone point me in the direction of a discussion on the pros & cons of seat position on long haul flights (ie window vs aisle, back vs front vs wing and so on).

Hope that all makes sense!